Skip to content
Navigation Menu
Toggle navigation
Sign in
In this repository
All GitHub Enterprise
↵
Jump to
↵
No suggested jump to results
In this repository
All GitHub Enterprise
↵
Jump to
↵
In this organization
All GitHub Enterprise
↵
Jump to
↵
In this repository
All GitHub Enterprise
↵
Jump to
↵
Sign in
Reseting focus
You signed in with another tab or window.
Reload
to refresh your session.
You signed out in another tab or window.
Reload
to refresh your session.
You switched accounts on another tab or window.
Reload
to refresh your session.
Dismiss alert
{{ message }}
git-mirror
/
linux
Public
Notifications
You must be signed in to change notification settings
Fork
0
Star
0
Code
Issues
0
Pull requests
0
Actions
Projects
0
Security
Insights
Additional navigation options
Code
Issues
Pull requests
Actions
Projects
Security
Insights
Files
90eec10
Documentation
arch
block
certs
crypto
drivers
firmware
fs
include
init
ipc
kernel
bpf
configs
debug
events
gcov
irq
livepatch
locking
power
printk
rcu
sched
time
trace
.gitignore
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
Makefile
acct.c
async.c
audit.c
audit.h
audit_fsnotify.c
audit_tree.c
audit_watch.c
auditfilter.c
auditsc.c
backtracetest.c
bounds.c
capability.c
cgroup.c
cgroup_freezer.c
cgroup_pids.c
compat.c
configs.c
context_tracking.c
cpu.c
cpu_pm.c
cpuset.c
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c
extable.c
fork.c
freezer.c
futex.c
futex_compat.c
groups.c
hung_task.c
irq_work.c
jump_label.c
kallsyms.c
kcmp.c
kexec.c
kexec_core.c
kexec_file.c
kexec_internal.h
kmod.c
kprobes.c
ksysfs.c
kthread.c
latencytop.c
membarrier.c
memremap.c
module-internal.h
module.c
module_signing.c
notifier.c
nsproxy.c
padata.c
panic.c
params.c
pid.c
pid_namespace.c
profile.c
ptrace.c
range.c
reboot.c
relay.c
resource.c
seccomp.c
signal.c
smp.c
smpboot.c
smpboot.h
softirq.c
stacktrace.c
stop_machine.c
sys.c
sys_ni.c
sysctl.c
sysctl_binary.c
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c
utsname.c
utsname_sysctl.c
watchdog.c
workqueue.c
workqueue_internal.h
lib
mm
net
samples
scripts
security
sound
tools
usr
virt
.get_maintainer.ignore
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile
README
REPORTING-BUGS
Breadcrumbs
linux
/
kernel
/
jump_label.c
Blame
Blame
Latest commit
History
History
522 lines (431 loc) · 12.5 KB
Breadcrumbs
linux
/
kernel
/
jump_label.c
Top
File metadata and controls
Code
Blame
522 lines (431 loc) · 12.5 KB
Raw
/* * jump label support * * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> * Copyright (C) 2011 Peter Zijlstra * */ #include <linux/memory.h> #include <linux/uaccess.h> #include <linux/module.h> #include <linux/list.h> #include <linux/slab.h> #include <linux/sort.h> #include <linux/err.h> #include <linux/static_key.h> #include <linux/jump_label_ratelimit.h> #ifdef HAVE_JUMP_LABEL /* mutex to protect coming/going of the the jump_label table */ static DEFINE_MUTEX(jump_label_mutex); void jump_label_lock(void) { mutex_lock(&jump_label_mutex); } void jump_label_unlock(void) { mutex_unlock(&jump_label_mutex); } static int jump_label_cmp(const void *a, const void *b) { const struct jump_entry *jea = a; const struct jump_entry *jeb = b; if (jea->key < jeb->key) return -1; if (jea->key > jeb->key) return 1; return 0; } static void jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) { unsigned long size; size = (((unsigned long)stop - (unsigned long)start) / sizeof(struct jump_entry)); sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); } static void jump_label_update(struct static_key *key); void static_key_slow_inc(struct static_key *key) { STATIC_KEY_CHECK_USE(); if (atomic_inc_not_zero(&key->enabled)) return; jump_label_lock(); if (atomic_inc_return(&key->enabled) == 1) jump_label_update(key); jump_label_unlock(); } EXPORT_SYMBOL_GPL(static_key_slow_inc); static void __static_key_slow_dec(struct static_key *key, unsigned long rate_limit, struct delayed_work *work) { if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { WARN(atomic_read(&key->enabled) < 0, "jump label: negative count!\n"); return; } if (rate_limit) { atomic_inc(&key->enabled); schedule_delayed_work(work, rate_limit); } else { jump_label_update(key); } jump_label_unlock(); } static void jump_label_update_timeout(struct work_struct *work) { struct static_key_deferred *key = container_of(work, struct static_key_deferred, work.work); __static_key_slow_dec(&key->key, 0, NULL); } void static_key_slow_dec(struct static_key *key) { STATIC_KEY_CHECK_USE(); __static_key_slow_dec(key, 0, NULL); } EXPORT_SYMBOL_GPL(static_key_slow_dec); void static_key_slow_dec_deferred(struct static_key_deferred *key) { STATIC_KEY_CHECK_USE(); __static_key_slow_dec(&key->key, key->timeout, &key->work); } EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); void jump_label_rate_limit(struct static_key_deferred *key, unsigned long rl) { STATIC_KEY_CHECK_USE(); key->timeout = rl; INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); } EXPORT_SYMBOL_GPL(jump_label_rate_limit); static int addr_conflict(struct jump_entry *entry, void *start, void *end) { if (entry->code <= (unsigned long)end && entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start) return 1; return 0; } static int __jump_label_text_reserved(struct jump_entry *iter_start, struct jump_entry *iter_stop, void *start, void *end) { struct jump_entry *iter; iter = iter_start; while (iter < iter_stop) { if (addr_conflict(iter, start, end)) return 1; iter++; } return 0; } /* * Update code which is definitely not currently executing. * Architectures which need heavyweight synchronization to modify * running code can override this to make the non-live update case * cheaper. */ void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, enum jump_label_type type) { arch_jump_label_transform(entry, type); } static inline struct jump_entry *static_key_entries(struct static_key *key) { return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK); } static inline bool static_key_type(struct static_key *key) { return (unsigned long)key->entries & JUMP_TYPE_MASK; } static inline struct static_key *jump_entry_key(struct jump_entry *entry) { return (struct static_key *)((unsigned long)entry->key & ~1UL); } static bool jump_entry_branch(struct jump_entry *entry) { return (unsigned long)entry->key & 1UL; } static enum jump_label_type jump_label_type(struct jump_entry *entry) { struct static_key *key = jump_entry_key(entry); bool enabled = static_key_enabled(key); bool branch = jump_entry_branch(entry); /* See the comment in linux/jump_label.h */ return enabled ^ branch; } static void __jump_label_update(struct static_key *key, struct jump_entry *entry, struct jump_entry *stop) { for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { /* * entry->code set to 0 invalidates module init text sections * kernel_text_address() verifies we are not in core kernel * init code, see jump_label_invalidate_module_init(). */ if (entry->code && kernel_text_address(entry->code)) arch_jump_label_transform(entry, jump_label_type(entry)); } } void __init jump_label_init(void) { struct jump_entry *iter_start = __start___jump_table; struct jump_entry *iter_stop = __stop___jump_table; struct static_key *key = NULL; struct jump_entry *iter; jump_label_lock(); jump_label_sort_entries(iter_start, iter_stop); for (iter = iter_start; iter < iter_stop; iter++) { struct static_key *iterk; /* rewrite NOPs */ if (jump_label_type(iter) == JUMP_LABEL_NOP) arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); iterk = jump_entry_key(iter); if (iterk == key) continue; key = iterk; /* * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH. */ *((unsigned long *)&key->entries) += (unsigned long)iter; #ifdef CONFIG_MODULES key->next = NULL; #endif } static_key_initialized = true; jump_label_unlock(); } #ifdef CONFIG_MODULES static enum jump_label_type jump_label_init_type(struct jump_entry *entry) { struct static_key *key = jump_entry_key(entry); bool type = static_key_type(key); bool branch = jump_entry_branch(entry); /* See the comment in linux/jump_label.h */ return type ^ branch; } struct static_key_mod { struct static_key_mod *next; struct jump_entry *entries; struct module *mod; }; static int __jump_label_mod_text_reserved(void *start, void *end) { struct module *mod; mod = __module_text_address((unsigned long)start); if (!mod) return 0; WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); return __jump_label_text_reserved(mod->jump_entries, mod->jump_entries + mod->num_jump_entries, start, end); } static void __jump_label_mod_update(struct static_key *key) { struct static_key_mod *mod; for (mod = key->next; mod; mod = mod->next) { struct module *m = mod->mod; __jump_label_update(key, mod->entries, m->jump_entries + m->num_jump_entries); } } /*** * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() * @mod: module to patch * * Allow for run-time selection of the optimal nops. Before the module * loads patch these with arch_get_jump_label_nop(), which is specified by * the arch specific jump label code. */ void jump_label_apply_nops(struct module *mod) { struct jump_entry *iter_start = mod->jump_entries; struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; struct jump_entry *iter; /* if the module doesn't have jump label entries, just return */ if (iter_start == iter_stop) return; for (iter = iter_start; iter < iter_stop; iter++) { /* Only write NOPs for arch_branch_static(). */ if (jump_label_init_type(iter) == JUMP_LABEL_NOP) arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); } } static int jump_label_add_module(struct module *mod) { struct jump_entry *iter_start = mod->jump_entries; struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; struct jump_entry *iter; struct static_key *key = NULL; struct static_key_mod *jlm; /* if the module doesn't have jump label entries, just return */ if (iter_start == iter_stop) return 0; jump_label_sort_entries(iter_start, iter_stop); for (iter = iter_start; iter < iter_stop; iter++) { struct static_key *iterk; iterk = jump_entry_key(iter); if (iterk == key) continue; key = iterk; if (within_module(iter->key, mod)) { /* * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH. */ *((unsigned long *)&key->entries) += (unsigned long)iter; key->next = NULL; continue; } jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); if (!jlm) return -ENOMEM; jlm->mod = mod; jlm->entries = iter; jlm->next = key->next; key->next = jlm; /* Only update if we've changed from our initial state */ if (jump_label_type(iter) != jump_label_init_type(iter)) __jump_label_update(key, iter, iter_stop); } return 0; } static void jump_label_del_module(struct module *mod) { struct jump_entry *iter_start = mod->jump_entries; struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; struct jump_entry *iter; struct static_key *key = NULL; struct static_key_mod *jlm, **prev; for (iter = iter_start; iter < iter_stop; iter++) { if (jump_entry_key(iter) == key) continue; key = jump_entry_key(iter); if (within_module(iter->key, mod)) continue; prev = &key->next; jlm = key->next; while (jlm && jlm->mod != mod) { prev = &jlm->next; jlm = jlm->next; } if (jlm) { *prev = jlm->next; kfree(jlm); } } } static void jump_label_invalidate_module_init(struct module *mod) { struct jump_entry *iter_start = mod->jump_entries; struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; struct jump_entry *iter; for (iter = iter_start; iter < iter_stop; iter++) { if (within_module_init(iter->code, mod)) iter->code = 0; } } static int jump_label_module_notify(struct notifier_block *self, unsigned long val, void *data) { struct module *mod = data; int ret = 0; switch (val) { case MODULE_STATE_COMING: jump_label_lock(); ret = jump_label_add_module(mod); if (ret) jump_label_del_module(mod); jump_label_unlock(); break; case MODULE_STATE_GOING: jump_label_lock(); jump_label_del_module(mod); jump_label_unlock(); break; case MODULE_STATE_LIVE: jump_label_lock(); jump_label_invalidate_module_init(mod); jump_label_unlock(); break; } return notifier_from_errno(ret); } struct notifier_block jump_label_module_nb = { .notifier_call = jump_label_module_notify, .priority = 1, /* higher than tracepoints */ }; static __init int jump_label_init_module(void) { return register_module_notifier(&jump_label_module_nb); } early_initcall(jump_label_init_module); #endif /* CONFIG_MODULES */ /*** * jump_label_text_reserved - check if addr range is reserved * @start: start text addr * @end: end text addr * * checks if the text addr located between @start and @end * overlaps with any of the jump label patch addresses. Code * that wants to modify kernel text should first verify that * it does not overlap with any of the jump label addresses. * Caller must hold jump_label_mutex. * * returns 1 if there is an overlap, 0 otherwise */ int jump_label_text_reserved(void *start, void *end) { int ret = __jump_label_text_reserved(__start___jump_table, __stop___jump_table, start, end); if (ret) return ret; #ifdef CONFIG_MODULES ret = __jump_label_mod_text_reserved(start, end); #endif return ret; } static void jump_label_update(struct static_key *key) { struct jump_entry *stop = __stop___jump_table; struct jump_entry *entry = static_key_entries(key); #ifdef CONFIG_MODULES struct module *mod; __jump_label_mod_update(key); preempt_disable(); mod = __module_address((unsigned long)key); if (mod) stop = mod->jump_entries + mod->num_jump_entries; preempt_enable(); #endif /* if there are no users, entry can be NULL */ if (entry) __jump_label_update(key, entry, stop); } #ifdef CONFIG_STATIC_KEYS_SELFTEST static DEFINE_STATIC_KEY_TRUE(sk_true); static DEFINE_STATIC_KEY_FALSE(sk_false); static __init int jump_label_test(void) { int i; for (i = 0; i < 2; i++) { WARN_ON(static_key_enabled(&sk_true.key) != true); WARN_ON(static_key_enabled(&sk_false.key) != false); WARN_ON(!static_branch_likely(&sk_true)); WARN_ON(!static_branch_unlikely(&sk_true)); WARN_ON(static_branch_likely(&sk_false)); WARN_ON(static_branch_unlikely(&sk_false)); static_branch_disable(&sk_true); static_branch_enable(&sk_false); WARN_ON(static_key_enabled(&sk_true.key) == true); WARN_ON(static_key_enabled(&sk_false.key) == false); WARN_ON(static_branch_likely(&sk_true)); WARN_ON(static_branch_unlikely(&sk_true)); WARN_ON(!static_branch_likely(&sk_false)); WARN_ON(!static_branch_unlikely(&sk_false)); static_branch_enable(&sk_true); static_branch_disable(&sk_false); } return 0; } late_initcall(jump_label_test); #endif /* STATIC_KEYS_SELFTEST */ #endif /* HAVE_JUMP_LABEL */
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
You can’t perform that action at this time.